Semi-automatic pneumatic guns are well know in the firearm arts. A well known type of pneumatic gun is the paintball gun. The paintball gun is a pneumatic gun that propels gelatinous balls filled with a marking paint, called paintballs. Paintball guns are generally used for recreational purposes including mock battles where the idea is to shoot the opposing team members. The paintballs break when they strike an opponent and mark the opponent with the paint. Another common use for paintball guns is the marking of cattle by ranchers for identification.
There are two basic types of pneumatic paintball guns: open bolt and closed bolt. The bolt is the part of a gun that moves the ammunition into the barrel of the gun, in this case the ammunition being a paintball. In the open bolt system, the bolt is normally in the rearward position. When the trigger is pulled, the bolt moves forward pushing a paintball into the barrel of the gun. A blast of propellant then pushes the paintball out of the gun. The propellant is usually CO.sub.2, compressed air or nitrogen. The bolt is then returned to the rearward, or open, position awaiting the next pull of the trigger.
In the closed bolt system, the bolt is normally in the forward position with the paintball already in the barrel. When the trigger is pulled, a blast of propellant pushes the path. When the bolt reaches the fall rearward position, it slides forward and pushes the paintball into the barrel. It remains in the forward position with the paintball in the barrel until the trigger is pulled again.
A non-semiautomatic firearm, also known as pump action or bolt action, would require the user to manually move the bolt after each pull of the trigger. A semi-automatic firearm is one in which a full cycle of the bolt is accomplished by each pull of the trigger; a full cycle being both firing and reloading of the ammunition. A fully automatic firearm is one in which the bolt will continue to fully cycle until the trigger is released. Pneumatic guns, such as paintball guns, are also available as automatic, semi-automatic or non-semiautomatic versions.
Pneumatic guns, especially paintball guns, have been the subject of many patents. Most of the prior art relates either to conversion of non-semiautomatic guns to semi-automatic guns or to improvement in the bolt action and propellant delivery systems. U.S. Pat. No. 5,503,137 to Fusco demonstrates a method of converting a non-semiautomatic paintball gun to a semi-automatic gun. U.S. Pat. No. 4,936,282 to Dobbins et al. demonstrates a "gas powered gun" that can either be non-semiautomatic or semiautomatic within the same gun.
One of the limiting factors of semi-automatic firearms and pneumatic guns is the users ability to continually pull the trigger in a rapid manner when higher rates of fire are desired. Human finger speed can be quick for only a short period of time and would not be continually uniform. The use of a fully automatic gun is often cost prohibitive and fully automatic guns are sometimes not allowed in paintball tournaments. Fully automatic guns also have complicated internal mechanisms which make them more prone to jamming and breaking and makes them harder to fix. The prior art has not addressed these issues. Therefore, it can be appreciated that there is room in the art for significant improvement on the prior art with regard to the trigger action. The present invention addresses these needs.